IS92] NEW-YORK MICROSCOPICAL SOCIETY. 11 



cent per inch is secured in the section of the rail under drop tests, 

 often exceeding the elongation of rails much lower in carbon. 



It will take many years of experience in the use of high-grade 

 steel rails to convince some people that hard steel can be a ma- 

 terial which is tough and not brittle, and one which, when the 

 elastic limits are exceeded, will still elongate to any per cent be- 

 fore rupture. 



One of the best illustrations of hard and tough structure in 

 steel is in the modern armor-piercing projectiles. A 6-inch loo- 

 pound conical projectile, fired with a velocity of 2,150 feet per 

 second, striking a steel armor plate with 2,800 foot tons of energy* 

 can be partially embedded therein and rebound with its point 

 hardly dulled or its polish diminished. 



Specimen No. 30 is a piece of nickel armor plate steel of fine 

 structure, the tensile strength averaging over 200,000 pounds per 

 square inch, with a limited elongation of i to 2 per cent. Only 

 half of this tensile strength is obtained in thick armor plates. 



The size and character of the grain in rail steel is a matter of 

 vital importance for the safety and economy of railroad opera- 

 tions. It is the fine texture of the steel rail which has rendered 

 possible the development of our railway system to 163,000 miles 

 of main tracks and 45,000 miles of sidings. In 1890, 1,100,000 

 tons of steel rails were put into railway tracks, and 3,125,000 tons 

 used for structural purposes. It is hardly a quarter of a century 

 since Bessemer-steel rails were first used to replace iron rails, and 

 in this brief time oceans and continents are crossed, and the 

 nations of the globe are in touch through the fine structure of 

 steel. 



LIST OF SPECIMENS. 



1. Compressed steel for ordnance, from ingot. 



2. Test bar from same steel after the hydraulic forging. 



3. Test bar from same steel after heat treatment. 



4. Specimen of etched steel from No. i. 



5. Specimen of etched steel from No. 2. 



6. Specimen of etched steel from No. 3. 



7. Specimen of etched steel from Bessemer rail ingot. 



8. Piece of Bessemer rail ingot. 



9. Piece of Bessemer rail ingot, showing pine-tree crystals. 



